Furnace



J. U. MCDONALD.

FURNACE.

APPLICATION FILED SEPT. 15, 1919.

Patented Aug 17 1920..

UNITED STATES JOHN URBAN MCDONALD, {BF DECATUR, ILLINOIS.

FURNAGE.

Application filed September 15, 1919.

To all whom it may concern: 7

Be it known that I, J OHN URBAN McDoN- ALI), a citizen of the UnitedStates, and residing at Decatur, in the county of Macon reducing it to afine powder and injecting it.

into a zone of intense heat in the presence of sufficient but nottoo'much air which is so thoroughly mixed with the powdered fuel thatcomplete and extremely rapid combus-' tion occurs. This results in aclear blue white flame which can be accurately controlled and varied asdesired. The furnace in which the combustion is completed may varywidely in shape and dimensions, but the form and construction of thechamber in which the fuel is ignited and in which the combustion beginsis of importance and forms the subject matter of this present invention.

As all powdered coal embodies a greater or less amount of ash whichliquefies in the intense heat of properly burnt coal, theignitionchamber should be so constructed that the liquid slag will notbe revented from freely flowing therefrom. have therefore so constructedand proportioned the ignition chamber that the injected fuel will bedirected toward the highly heated inclined bottom which soon becomescoated with liquid slag and is protected thereby. The fuel be comeshighly heated as it leaves the injector and bursts into flame at aboutthe instant it enters the ignition chamber, and the flame is thrown backupon itself by the walls of this chamber and travels above the freshincoming fuel giving off some of its heat thereto.

In the accompanying drawing, Figure 1 is a central vertical longitudinalsection of a furnace embodying my improved ignition chamber. Fig. 2 is asection on the line 2-2 of Fig. 1.

Similar reference characters refer to like parts throughout the severalviews.

The drawing shows conventionally a well known fire-tube boiler l and thefront furnace wall 2, rear wall 8, covering 4, side walls 9 and smokepipe 5 therefor. The coal is conducted into the furnace in the form of apowder by means of a current of air through an injector consisting ofthe pipe 6 in the usual, manner, this pipebeing central Specification ofLetters Patent.

Patented Aug. 1'7, 1920. Serial No. 323,810.

with a second pipe 7, preferably of refractory material, the spacebetween the two pipes serving to admit air to the furnace. Just back ofthe front wall 2 I prefer to construct a tank or receptacle 8 to receivethe slag and cinders.

The ignition chamber 13 is positioned from four to eight feet from thewall 2 and is so constructed that its bottom 14 slopes down forwardlyand the chamber is of such a height that the fuel from the injectorstrikes the bottom just back of its front edge as indicated bv thearrows in Fig. 1. I prefer this floor to be in the form of atrough sothat the slag formed by melting the ash of the fuel may flow down to thetank 8. Above the floor is an arch 15 tapering rearwardly to the endwall 16. The crown of this arch is preferably thin enough to transmitheat from its lower to its upper surface and thus avoids being melted asin the case with heavy arches. An apron 10 slopes down from the front ofthe bottom 14- toward the tank 8.

The end of the injector is spaced sufiiciently from the front face ofthe ignition chamber to avoid being melted, by the intense heat justwithin the ignition chamber, but the fuel as it leaves the injector isexposed to this heat so that it begins to burn as it enters thischamber. All of the coal, excepting the ash, becomes a as and ignitesunder this intense heat and the flame thereof turns upward and outward,passing over the incoming fuel without mixing or inter faring therewithand then passes to the atmosphere, preferably back over the arch '15grid ifdesired, through the tubes of the oiler.

A portion of the heat of the waste gases passing to the stack 5 may besaved by placing a pro-heater 18 in the breeching this stack, the pipe20 being connected to the fan=(not shown) which supplies the air for thefuel injector. The greatest heat is within and just in front of theignition chamber and the ractically incandescent gases pass rearwarc lybetween the boiler andthe top 10f the ignition chamber.

1. An apparatus for burning powdered fuel comprising a front wall; arearwardly tapering ignition chamber spaced from said wall a d acombustion chamber between them, afi id an injector for powdered fueland air mounted in said well and extending partially across thecombustion chamber toward the ignition chamber and having its dischargeend substantially level with the bottom of the ignition chamber so thatthe air and fuel will impinge thereon and the flame from the fuel. maybe deflected upwardly and forwardly and pass out over and pre-heat theincoming mixture before passing upwardly and rearwardly over the top ofthe ignition chamber.

2. An apparatus for burning powdered fuel comprising a frontwall, arearwardly tapering ignition chamber spaced from said wall and acombustion chamber between them, and an injector for powdered fuel andair mounted in said wall and extending I partially across the combustionchamber toward the ignition chamber and having'its discharge endsubstantially level with the bottom of the ignition chamber so that theair and fuel will impinge thereon and the flame from the fuel may bedeflected upwardly and forwardly and pass out over and preheat theincoming mixture before passing upwardly and rearwardly over the top ofthe ignition chamber, the top of the ignition chamber being thin so asto transmit heat therethrough to the space above it and preventexcessive heating of said top.

3. A boiler furnace for burning powdered fuel comprising a front Wallextending up tive to the injector that the blast of incoming fuel willstrike it at an acute angle.

4. An ignition chamber for furnaces adapted to receive a blast of fueland air comprising a rear wall, a bottom sloping up to a rear wall andan arch resting on said bottom and sloping down to the rear wall,

the upper surface of the bottom being in two parts sloping down towardeach other and toward the central vertical plane of the structure. l

5. An ignition chamber for furnaces adapted to receive a blast of fueland air comprising a rear wall, a bottom sloping up to a rear wall andan arch. resting on said bottom and sloping down to the rear wall, theupper surface of the bottom being in two parts sloping down toward eachother and toward the central vertical plane of the structure, and aninjector for powdered fuel and air directed toward said bottom so thatthe fuel will im inge thereon.

JOHl l URBAN MCDONALD.

